IADR Abstract Archives
Dynamic Cyclic Fatigue of Four Rotary Instruments in S-shaped Canals
Objectives: This study was conducted to compare the dynamic cyclic fatigue resistance of Race EVO (RE), VDW ROTATE (VR), ONE CURVE (OC), and 2SHAPE (TS) in double S-shaped canals at body temperature.
Methods: Four types of rotary instruments (each=15, total=60), Race Evo, VDW Rotate, One Curve, and 2Shape were tested in a double S-shaped stainless-steel artificial canal (coronal curve:60°, 5mm radius, and apical curve:70°, 2 mm radius). These instruments were assessed at a simulated body temperature (37°± 0.5°C), and moved in a dynamic motion until fracture. The speeds were set at 100 and 200 mm/min for the descending and ascending motion respectively. The endo motor speed/torque were set according to manufacturer recommendation. The number of cycles to failure (NCF) was calculated with aid of videoing camera. The fractured pieces lengths were measured using digital Vernier. Fractographic analysis of fractured surfaces was also carried out using Scanning Electron Microscopy (SEM). Data of NCF and fragment length were analyzed by using one-way analysis of variance and Tukey post hoc. The level of significance was set at p value of 0.05.
Results: The OC instrument had significantly higher NCF (mean±SD=3749.93±675.23) compared to RE (1698.46±398.11), VR (1858.46±382.48), and TS (1234.33±256.21) (p<0.001). No significant difference was detected between RE and VR (p>0.05). TS had significantly the lowest NCF compared to the rest (p<0.05). No significant difference was detected at the fracture site between the groups (p<0.05). SEM test predominantly confirmed ductile mode of fracture.
Conclusions: ONE CURVE rotary instrument had the greatest resistance to dynamic cyclic fatigue at body temperature compared to both Race EVO and VDW ROTATE, whilst the 2SHAPE showed the lowest value of resistance to fracture.
Methods: Four types of rotary instruments (each=15, total=60), Race Evo, VDW Rotate, One Curve, and 2Shape were tested in a double S-shaped stainless-steel artificial canal (coronal curve:60°, 5mm radius, and apical curve:70°, 2 mm radius). These instruments were assessed at a simulated body temperature (37°± 0.5°C), and moved in a dynamic motion until fracture. The speeds were set at 100 and 200 mm/min for the descending and ascending motion respectively. The endo motor speed/torque were set according to manufacturer recommendation. The number of cycles to failure (NCF) was calculated with aid of videoing camera. The fractured pieces lengths were measured using digital Vernier. Fractographic analysis of fractured surfaces was also carried out using Scanning Electron Microscopy (SEM). Data of NCF and fragment length were analyzed by using one-way analysis of variance and Tukey post hoc. The level of significance was set at p value of 0.05.
Results: The OC instrument had significantly higher NCF (mean±SD=3749.93±675.23) compared to RE (1698.46±398.11), VR (1858.46±382.48), and TS (1234.33±256.21) (p<0.001). No significant difference was detected between RE and VR (p>0.05). TS had significantly the lowest NCF compared to the rest (p<0.05). No significant difference was detected at the fracture site between the groups (p<0.05). SEM test predominantly confirmed ductile mode of fracture.
Conclusions: ONE CURVE rotary instrument had the greatest resistance to dynamic cyclic fatigue at body temperature compared to both Race EVO and VDW ROTATE, whilst the 2SHAPE showed the lowest value of resistance to fracture.